Composition and a method for treating molten metals



fiee Patented July 3, 1%62 3,042,484 COMPOSITION AND A METHOD FOR TREATENG MOLTEN METALS Walter Dale Maring, Shelby, Ind. No Drawing. Filed Mar. 23, 1960, Ser. No. 16,917 2 Claims. (CI. 23-14) This invention relates to a composition and a method for treating molten metals, in particular, steel, when such molten metal is poured into a mold.

When molten steel or other molten metals are poured into a mold, the atmosphere in the mold and surrounding the ladle stream contaminates the metal, which causes fissures and seams in the resulting casting which then in most instances is scrapped.

Further, when a molten metal, such as steel, is poured at a rapid rate from a ladle into a mold, the turbulently flowing metal tends to entrap air. On solidification of the outer layer of metal in the mold, the entrapped air (or at least the nitrogen content of the entrapped air) often causes the generation of extremely high pressures within the casting, to the point where explosions take place. Such explosions have killed and injured many workmen in the steel industry when large ingots are produced for rolling purposes. Of course, the ingots have to be scrapped after such explosions.

The composition and method of the present invention eliminates the above mentioned hazards and disadvantages.

According to the present invention, wherein for example, molten steel is poured into cast iron molds, the bottom of the mold is sealed. The mold may be, and preferably is, preheated to a temperature, say, of 250 degrees to 350 degrees Fahrenheit. At this time a lump or chunk of solid compound of carbon-dioxide and an inert gas, specifically, argon gas, is dropped into the bottom of the mold. The compound being unstable, starts decomposition immediately, reverting to gases, rapidly expelling all atmosphere from the mold.

Carbon-dioxide and argon, under ordinary conditions, bear no natural afiinity one to the other. As fast as decomposition takes place and the solids are returned to gases, the materials split oli or separate. When the mold is filled with gas and gas is pouring over the top sides of the mold, the pouring of the metal is started. As the metal is being poured, and the mold fills, the lump or chunk of solid compound floats on the top of the molten metal, continuing decomposition.

When the mold has been filled to the desired level, there are solids decomposing on the top of the casting, and they continue to decompose until extinct. At this time the top of the casting has solidified.

The protective gas blanket completely protects the molten metal against oxidation and entrapment of air. Actually, the solid unstable compound floats on top of the molten metal during and after the pouring operation.

Approximately one (1) pound of the above noted compound may be used for one (1) ton of molten metal.

The compound in question contains from 1 to 30% (by weight) and preferably from 14 to 21% of inert gas, sp cificaily, argon, the remainder being carbon-dioxide.

The compound is produced by mechanically saturating liquid carbon-dioxide with argon gas under confinement, and further releasing the saturated liquid carbon-dioxide into a suitable expansion chamber, bringing about instantaneous solidification in the ratios indicated in the next preceding paragraph. The temperature of the solidified lump or chunk is approximately minus one-hundred degrees Fahrenheit, at which temperature the compound is stable.

By way of a specific example, in casting a steel ingot Weighing about 28,000 pounds, I added a 10 pound chunk of a compound containing about 15% argon, the remainder being carbon-dioxide. The cost of the complete protection thus afforded to the steel amounts to about 7 cents per ton.

The methods of this invention involve a material that is safe, non-explosive, easy to handle, clean and effective to eliminate the above noted hazards and disadvantages at very little cost.

Many details may be varied without departing from the spirit of this invention. Therefore, the scope of the appended claims is not to be limited except by their terms.

I claim:

1. A calthrate complex of carbon-dioxide and argon, said complex containing from 1 to 30% argon, the remainder being essentially carbon-dioxide, said complex being stable at about 100 degrees Fahrenheit but unstable at higher temperatures.

2. A method of preparing a calthrate complex contain ing from 14 to 21% of argon, the remainder being carbondioxide; said complex being stable at l00 F.; said method comprising saturating liquid carbon-dioxide with argon while confining said carbon-dioxide and thereafter releasing said carbon-dioxide into an expansion chamber, whereby said complex is formed in solid state.

References Cited in the file of this patent UNITED STATES PATENTS Kinzel Nov. 15, 1932 Cape Feb. 26, 1946 OTHER REFERENCES 

1. A CALTHRATE COMPLEX OF CARBON-DIOXIDE AND ARGON, SAID COMPLEX CONTAINING FROM 1 TO 30% ARGON, THE REMAINDER BEING ESSENTIALLY CARBON-DIOXIDE, SAID COMPLEX BEING STABLE AT ABOUT -100 DEGREES FAHRENHEIT BUT UNSTABLE AT HIGHER TEMPERATURES. 